Muzzle Velocity Questions

shakeyjake

shakeyjake

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My damn chroney has been acting up for over half a year now and I'm trying to estimate the MV in my rifle. It's a Rem 700 Tac with a 20 inch tube. My loads are 45.5 gr Varget under a 178 gr Amax. I've been on Google all weekend trying to find some kind of calculator with not much luck. The charge is over max according to Lymans book but the brass is doing fine and I'm getting good results. I figured with the shorter barrel I wanted a hotter load to get the velocity up for those long shots. What do you think? Any help would be greatly appreciated.



Condolences to friends & family of Chris Kyle
 
I figured with the shorter barrel I wanted a hotter load to get the velocity up for those long shots. What do you think?
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I do have an issue with that logic. Too hot is too hot regardless of the length of the barrel. As to the brass being okay, how many times has it been fired with that load? As well, being an extreme powder, Varget is not as sensitive to changes in temperature as many other powders, but it still varies a bit. As such the pressure, and the velocity will still be a little lower on a cold winter day, than on a hot summer day. At a guess, and it's only a guess, I would estimate somewhere around 2600fps.
 
Muzzle blast does play havok on readings. Try moving the chrony out a little further away until you see results. But stubblejumber is right, it sounds like your load is too hot. Accuracy beets speed anyday. If you want more speed, try a bigger caliber for longer shots...?
 
The brass is on it's 3rd reload. Yea, I'm thinking 2600 is probably in the ball park. I've shot these loads 2 weeks ago at about -20C and also last summer at 34C with good results. my 223wssm loads on the other hand had a pretty stiff bolt in summer so I pulled the projectile on those. Hell of a bark!
 
Been over max for my Nemesis, some peoples around here just advised me not to do it and i stopped doing it, if you want to get more velocity out of your 20 inch tube, instead of going over max just try the R-17 with 178 gr bullet, beat Varget in speed and is as accurate... JP.
 
I like your thinking, as soon as I can afford to upgrade I'll go 338 or more unlikely a 50. Seems the hotter the load, the better it shoots. I guess you have to draw the line somewhere though. Next loads I'm trying are using a 190 gr Berger......easier to predict drop than wind effects.
Thanks for the input.
 
shakeyjake said:
I like your thinking, as soon as I can afford to upgrade I'll go 338 or more unlikely a 50. Seems the hotter the load, the better it shoots. I guess you have to draw the line somewhere though. Next loads I'm trying are using a 190 gr Berger......easier to predict drop than wind effects.
Thanks for the input.
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...And switching to R-17 will please you... JP.
 
Never even thought of R17. Doesn't even show up in some of my manuals. Going to have to get me some as it looks like it may work for a few calibers.
 
R17 might be decent but will fluctuate quite a but with temp. Stick with varget. And with that load in that barrel you are probably closer to 2675-2700.
 
I was just screwing around with a ballistics program and going by my POI at 400 yards MV looks like 2700ish. Alliant claims it's a stable powder in terms of hot and cold temperature, but hands on info is the best. Thanks c4pyro.
Nice avatar
 
That's really low. Hodgdons reloading info shows 45.0 max from 175-180 grain bullets. I have loaded two rifles past that. That is not saying you should, but my custom rifle, lapua brass, 210m primers was 45.7g. Shot 2740 fps, brass was decent. The ther was for a standard erm 5R and was load components were the same with 45.2 grains varget. Max is usually to play it safe as a company and to get best life out of your components, but that's where the accuracy was and I wanted the high node for velocity so I pushed it. Just work up and look for pressure......honestly look for pressure....

The RL powders can give great accuracy, no question there but they do have temperature issues. If you can test, play and manage, go to town, but crap loads of people, use varget because its accurate and stable. Why do extra work....
 
45 grains of Varget with 175 SMK gave me 2650 in my 20" LTR before I rebarreled and I reloaded that same hornady brass over 15 times only fl sizing, no annealing. My buddies LTR shot 46 grains of varget safely again with the same bullet, hornady match brass and BR-2 primers with same results. Mine just was really accurate so I didn't go higher. Let your gun tell you what it can do not another Internet shooter. Accuracy is the ultimate goal but doing that with a higher velocity is always nice also. Your components, your call.
 
shakeyjake said:
I like your thinking, as soon as I can afford to upgrade I'll go 338 or more unlikely a 50. Seems the hotter the load, the better it shoots. I guess you have to draw the line somewhere though. Next loads I'm trying are using a 190 gr Berger......easier to predict drop than wind effects.
Thanks for the input.
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That's often the case. Keep safe and prudent of course.

That does sound like a very hot load, but it *might* be OK for you.
- what brass are you using? (how much does it weigh)
- How long are you loading the bullets? (Remington .308s usually have long and somewhat sloppy throats)

If your primer pockets are loosening, that's a sure sign that you're too hot.

If you want high performance at long range, the most effective way to pursue that is with a higher performance bullet. A Berger 185LRBT or Hybrid immediately springs to mind (very high performance, and a very 'easy' bullet to get to shoot well). If you are interested in even more exotic bullets, consider the Berger 215 Hybrid or 230 Hybrid. Dunno what the twist rate is in your rifle (it might or might not handle these). But the very long Remington throat would be working in your favour. You won't be able to feed them from a magazine, but who cares.

shakeyjake said:
I was just screwing around with a ballistics program and going by my POI at 400 yards MV looks like 2700ish. Alliant claims it's a stable powder in terms of hot and cold temperature, but hands on info is the best. Thanks c4pyro.
Nice avatar
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You do what you can with what you've got, of course, but back-figuring speed from drop is a very sensitive to small errors (e.g. is it 400 yards or 405 yards? What is the actual size of your scope's so-called 'minutes'? What was the air temperature on the day you tested? To what precision do you know the location of the centre of your group at 400 and your group at 100?)

BTW 2700-ish does sound like more or less what you're probably getting.
 
I'll have to consider those hybrids. I've still got 73 of these current loads to send down range so I suppose I'll most likely be doing that before this spring. Then start fooling around with the 190 gr
 
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